Vacuum and pressure tubing



1 I J. A. KENNEDY 1,931,868

VACUUM AND PRESSURE TUBING Filed May 19, 1930 Patented Oct. 24, 1933 1,931,888 VACUUM AND PRESSURE TUBING Joseph A. Kennedy, Pawtucket, R. 1., assignor I to Anaconda Wire and Cable Company, New York, N. Y., a corporation of Delaware Application May 19, 1930. Serial No. 453,718

Claims. (Cl. 91'I0) This invention relates to a new and improved tubing for vacuum and pressure purposes containing no rubber in its structure, which is a substitute for, and for many purposes superior to, rubber hose and tubing. The invention also relates to the novel method herein disclosed for making this improved tubing.

One' of the more particular objects of the invention is to provide a tubing of the type above stated which will be adaptable to use in the operating of automobile windshield wipers by vacuum from the engine. To adequately serve such purpose the tubing must be impervious to penetration and resistant to attack and modification by water, oil, gasolene, outside weather conditions, etc.; must be able to withstand a substantial vacuum or pressure without leaking and continue in such use in exposed places under rough treatment for a considerable period of I time; must be sufiiciently flexible to permit bending in relatively sharp curves without collapsing or seriously obstructing its bore; and must have an ornamental or pleasing finish and appearance so that when used in positions exposed to view it will harmonize artistically with the color and finish of the automobile or other structure to which it is applied.

In producing an improved tubing having the above defined characteristics, I have developed a method of so treating a seamless woven tube as to give to it these characteristics. This treatment involves several and various steps, all of which are fully explained in the following specification in connection with the accompanying drawing.

With the above and other objects in view, as will hereinafter more specifically appear, my invention consists in .the features of construction and operation set forth in the following specification and illustrated in the accompanying drawing. In such drawing. I have illustrated certain specific embodiments of my invention, but it will be understood that the invention can be otherwise embodied and that the drawing is not to be construed as defining or limiting the scope of the invention, the claims appended hereto being relied upon for that purpose.

, Referring to the figures of the drawing,

Fig. 1 shows a fragment of tubing embodying my invention, a portion thereof being broken away to illustrate the elements of its construction; I

Figs. 2 and 3 are diagrammatic illustrations of apparatus suitable for producing such tubing.

In proceeding with the manufacture of myimproved tubing, I start with a base or body which, as illustrated in the drawing, is preferably a seamless woven tube 1, comprising flexible cotton warp strands 2 and one or more helical weft or filling strands 3 of round, hard-twisted .kraft 0 paper or other suitable material having desired qualities of strength and stiffness. These elements are closely combined by known methods of circular weaving to produce the tube 1 having any desired dimensions. 7 5

In being prepared for the purposes indicated, the tube is first treated with a liquid preserving compound. A suitable compound for this purpose is so-called linseed oil baking varnish, a known composition made of synthetic resin and vegetable oil, such as linseed oil and China-wood oil, which is convertible into a dry, inert, flexible condition by heat in the presence of air.

Such composition may be applied either from the interior or from the exterior of the tube. If applied from the interior, it may be applied in the course of weaving by being introduced through a hollow mandrel about which the woven tube is constructed, as described in my application Serial No. 279,441, filed May 21, 1928. If applied from the outside, such application may be made by passing the completed tube through a bath of the compound, with immersion of the tube in the bath long enough for penetration of the compound to the walls of the interior bore. 5, Impregnation of the preserving compound into the wall of the tube from the interior being more important than impregnation of the exterior part of the tube, since the exterior is protected by the later described lacquer covering, I prefer to apply it in the manner first described, as this method uses less of the compound and is therefore more economical. However, the protection which I claim is not limited to any specific means of applying the compound. ,95

The tubing thus treated is then dried and 1 cured at a temperature preferably of about 260 F. for a period of three hours more or less. This curing step may be carried out in a steam heated oven through-which fresh air is circulated to .100 maintain an even temperature and avoid danger of spontaneous combustion.

A diagrammatic illustration of apparatus for carrying out this part of the method is shown in Fig. 2, Where 4 designates a bath of the composition, typifying any means for applying it, and 5 represents a closed drying chamber or oven containing a heating coil 6 and having air circulating means 7, the tubing .being coiled up and supported so that the flowing air may have access lid to all of its parts. In some cases, the tubing may be subjected to heat and pressure by passage through a heated die before it is reeled or coiled.

The tubing is next coated externally with lacquer. For this purpose a coil of the tubing is supported on the reel 8 and drawn thence through a lacquering box or pot 9, wherein it receives a coating of lacquer solution. Various known preparations of nitrocellulose, or other cellulose compounds, with solvents and emollient oils may be used here. I prefer to use nitrocellulose containing a suitable content of castor oil, (which is an essentially non-drying oil) to keep it flexible, dissolved in any suitable solvent. From the lacquering pot the coated tube passes to a drier 10, and thence to a steam heated die 11. The drier may be any suitable chamber heated by any suitable means, in which the coated tube remains long enough for evaporation of the volatile solvent.

The die is a tube or ring surrounded by a steam jacket. In other words, it is a heated bushing, the bore of which is of such diameter as to fit the tube closely and apply pressure to the coating. Its function is to compact the coating and to close up the pores or pin holes formed by escape of the volatilized solvent through the skin which forms first on the coating being dried.

Sever ml coats of lacquer, preferably eight, are applieo'in this manner, the tubing passing a corresponding number of times through the apparatus described, or through a like number of duplications of such apparatus. Duplicate devices or elements corresponding to the parts thus diagrammatically illustrated may be combined in various ways by the designer within the scope of the present invention and of the appended claims.

Each of these successive operations applies an additional layer of the protective lacquer coating; and they all combine to make the composite lacquer coat indicated by 12 in Fig. 1. By applying this coat in successive increments I am able to control very accurately its thickness, density, and other qualities. Since the heated die treatment following each lacquer application compacts the lacquer and fills up the pinholes due to evaporation, a very dense and impervious coat is made very efficiently with a minimum expenditure of time, material and labor.

The lacquer treatments contribute various essential and desirable features to the finished tubing. One of the most important of these is to render the tubing air tight, and the treatment has proved so saisfactory in this respect that tubing made by my process will withstand differences between external and internal pressures up to 15 pounds per square inch. Another essential feature is to render the tube impervious to attack by the elements and various substances with which it may come into contact. Exhaustive tests have proved that the tubing fulfills these requirements to a very high degree. The lacquer coat has a high lustre and may be given any color desired by addition of dyes or pigments.

The improved form of tubing made by the method herein claimed is covered in my copending divisional application Serial No. 672,442, filed May 23, 1933.

What I claim and desire to secure by Letters Patent is:

1. A method of making tubing of the character described comprising coating a seamless woven tube with a preserving and oil and gasoline resisting substance, applying a flexible lacquer covering thereover, heating the tubing to drive oil the solvents and simultaneously subjecting the lacquer coating to heat and smoothing-pressure to provide a smooth, non-porous coating.

2. A method of making tubing for vacuum and pressure purposes, consisting of coating a seamless woven tube with a preserving compound, applying a lacquer covering thereover, and passing the lacquered tube first through a heated chamber and then through a heated die to close evaporation holes in and compact the lacquer covering.

3. A method of making tubing for vacuum and pressure purposes, providing a woven seamless tube body having longitudinal warps and helical filling, impregnating and coating the tube with a preserving and oil and gasolene resisting com pound, applying a plurality of lacquer coatings thereover, rapidly evaporating the lacquer solvents and then passing the tube through a heated die to close evaporation holes in the coating and leave the tubing of a uniform diameter and the outer surface thereof with a compacted and pollshed lacquer finish.

4. A method of making tubing for vacuum and pressure purposes, consisting of coating a seamless tube body with linseed oil baking varnish, passing the tube through a heated die to com= pact and set the coating, and applying a relatively strong and air tight flexible nitrocellulose lacquer covering thereover.

5. A method of making tubing for vacuum and pressure purposes, consisting of coating a seamless woven tube body with a preserving and oil and gasolene resisting compound, passing the tube through a heated die to compact the coating, applying a lacquer covering thereover, evaporating the lacquer solvents, and passing the tube through a heated die to close holes in the lacquer covering and provide its outer surface with a lustrous finish.

6. A method of making tubing for vacuum and pressure purposes, consisting of impregnating and coating a seamless woven tube body with a preserving and oil and gasolene resisting compound, applying a plurality of lacquer coatings thereover, evaporating the solvents of the coatings, and passing the tube through a heated die after each of said lacquer coatings to close evaporation holes in such coatings and compress and smooth them.

'7. A method of making tubing for vacuum and pressure purposes, consisting of coating a seamless woven tube body with a preserving and oil and gasolene resisting compound, passing the tube through a heated die to compact and set the coating, applying a plurality of flexible nitrocellulose lacquer coatings thereover, rapidly evaporating the lacquer solvents, and passing the tube through a heated die after each of said lacquer coatings.

8. A method of making woven tubing resistant to attack by water and oils, and impervious solidified by heat in the presence of air, pressing and smoothing such coating simultaneously on all sides of the tubing, with application of heat; applying to the coating so treated, after solidification thereof, a cellulosic lacquer solution, and drying said lacquer coating by heat and subsequently subjecting the latter coating to a rubbing heat and pressure step to compact the coating and close evaporation pores formed during said drying step.

which consists in progressively applying a coating oi lacquer externally on all sides of the tubing rapidly evaporating the lacquer solvents, and subsequently and progressively applying heat and pressure simultaneously to the coating on all sides of the-tubing.

JOSEPH A. KENNEDY. 

